User equipment, base station, communication control method, and radio communication system

ABSTRACT

A user equipment includes radio communication unit that performs radio communication with a base station over a communication channel formed by aggregating a plurality of component carriers. The user equipment has a measurement unit that measures a channel quality of the communication channel, and a controller that creates a measurement report using a result of the measurement and sends the measurement report to the base station. Each data signal transmitted over the communication channel is classified into any of two or more classes depending on a QoS requirement thereof. The radio communication unit receives control information related to a mapping between each of the plurality of component carriers and the class of each data signal from the base station, and the controller controls at least one of the measurement and the sending of the measurement report, according to a procedure which varies depending on the control information. A base station performs associated functions, according to a communication method involving allocation of data to component carriers based at least in part on channel quality criteria for different data classifications.

TECHNICAL FIELD

The present invention relates to a user equipment, a base station, acommunication control method, and a radio communication system.

BACKGROUND ART

In Long Term Evolution-Advanced (LTE-A), which is the next-generationcellular communication standard that is discussed in Third GenerationPartnership Project (3GPP), introduction of technology called carrieraggregation (CA) has been studied. Carrier aggregation is technologythat forms a communication channel between a user equipment (UE) and abase station (BS, or evolved Node B (eNB)) by aggregating a plurality offrequency bands that are supported in LTE, for example, and therebyimproves communication throughput. Each frequency band included in onecommunication channel that is formed by the carrier aggregation iscalled a component carrier (CC). The bandwidths of frequency bands thatare available in LTE are 1.4 MHz, 3.0 MHz, 5.0 MHz, 10 MHz, 15 MHz, and20 MHz. Accordingly, if five bands of 20 MHz are aggregated as componentcarriers, a communication channel of 100 MHz in total can be formed.

Component carriers that are included in one communication channel in thecarrier aggregation are not necessarily contiguous to one another in thefrequency domain. The mode in which component carriers are arrangedcontiguous to one another in the frequency domain is called a contiguousmode. On the other hand, the mode in which component carriers arearranged not contiguous to one another is called a non-contiguous mode.

Further, in the carrier aggregation, the number of component carriers inan uplink and the number of component carriers in a downlink are notnecessarily equal. The mode in which the number of component carriers inan uplink and the number of component carriers in a downlink are equalis called a symmetric mode. On the other hand, the mode in which thenumber of component carriers in an uplink and the number of componentcarriers in a downlink are not equal is called an asymmetric mode. Forexample, in the case of using two component carriers in an uplink andthree component carriers in a downlink, it can be called asymmetriccarrier aggregation.

Further, in LTE, any one of frequency division duplex (FDD) and timedivision duplex (TDD) can be used as duplex operation. Because thedirection of a link (uplink or downlink) of each component carrier doesnot change in time in FDD, FDD is better suited to the carrieraggregation compared to TDD.

Meanwhile, a handover, which is a basic technique for achieving themobility of a user equipment in the cellular communication standard, isone of the important subjects in LTE-A. In LTE, a user equipmentmeasures the communication quality with a serving base station (acurrently connected base station) and communication qualities withperipheral base stations and transmits a measurement report containingmeasurements to the serving base station. Receiving the measurementreport, the serving base station determines whether a handover should beperformed or not based on the measurements contained in the report.Then, if it is determined that a handover should be executed, a handoveris carried out among a source base station (the serving base stationbefore a handover), the user equipment, and a target base station (aserving base station after a handover) according to a prescribedprocedure (e.g. Patent Literature 1 below).

CITATION LIST Patent Literature

-   PTL 1: Japanese Unexamined Patent Application Publication No.    2009-232293

SUMMARY OF INVENTION Technical Problem

However, no case has been reported where active consideration is givento how to carry out a handover procedure in a radio communicationinvolving carrier aggregation.

For example, as described above, a measurement report in a typicalhandover procedure can contain results of measurements for acommunication channel with a serving base station and a communicationchannel with peripheral base stations. However, in a radio communicationinvolving carrier aggregation, if measurement is performed or ameasurement report is sent based on the quality levels of all componentcarriers of those communication channels, the time cost necessary forprocessing increases. Further, there is a concern that resourceefficiency decreases due to an increase in the amount of data. It istherefore an issue for the carrier aggregation technology to enhance theefficiency of processing from the start of measurement to the sending ofa measurement report.

Meanwhile, determination whether a handover that is executed based on ameasurement report should be performed or not affects the servicequality of a radio communication service. Therefore, it is desirable toenhance the efficiency of the above-described processing related to ameasurement report without degrading the service quality as much aspossible.

In light of the foregoing, it is desirable to provide a novel andimproved user equipment, base station, communication control method, andradio communication system that can efficiently execute processingrelated to a measurement report depending on a QoS requirement in aradio communication involving the carrier aggregation.

Solution to Problem

According to an embodiment of the present invention, an informationprocessing apparatus, such as a base station, is configured tocommunicate with another information processing apparatus, and includesa receiver configured to receive quality information regarding qualityof service for data to be transmitted. An allocating unit is included todetermine how to allocate the data on component carriers according tothe quality information. Also a notification unit is included andconfigured to notify the another information processing apparatus ofallocation information that specifies how the data is to be allocated onthe component carriers.

The allocating unit may allocate the data differently according to aquality information associated with a data classification for the data.

The allocating unit is configured to mix data with different quality ofservice criteria on a common communication channel using carrieraggregation of the component carriers.

The apparatus maps component carriers to quality of servicesclassifications for data set by the allocating unit, which enablesdynamic control at another information processing unit (such as a UE)from a time of starting channel quality measurement to providing ameasurement report to the information processing apparatus.

A processor may be included that determines whether to perform ahandover for the another information processing apparatus based onwhether the measurement report indicates that a better channel qualityis available to the another information processing apparatus from aperipheral information processing apparatus, the better channel qualitybeing better with respect to a predetermined threshold.

The predetermined threshold may be varied for respective of thecomponent carriers.

The allocating unit may be configured to select a mapping pattern forallocating data on the component carriers depending on one of variationof channel quality among the component carriers and resourceavailability of the respective component carriers.

The allocating unit determines the variation of channel quality amongcomponent carriers via a preceding channel quality report provided bythe another information processing apparatus.

The allocating unit determines the variation of channel quality amongcomponent carriers by requesting an auxiliary channel quality reportfrom the another information processing apparatus.

According to another embodiment, an information processing apparatus forcommunicating with another information processing apparatus uses aplurality of component carriers, and includes a receiver configured toreceive allocation information that specifies how data to be transmittedis to be allocated among component carriers. The apparatus also includesa control unit configured to execute a process in order to conduct ahandover procedure according to the allocation information, where theprocess can be one or more of transmitting a channel quality report ormeasurement report, or determining a timing when a measurement starts.

The allocation information may include information about how data isallocated on component carriers based on quality of service criteria.

The data may be categorized into one of a plurality of quality ofservice classifications.

The control unit is configured to send measurement data to the anotherinformation processing apparatus when the control unit determines that achannel quality available from a peripheral information processingapparatus is higher than a channel quality from the another informationprocessing apparatus.

The control unit is configured to determine the channel quality beinghigher based on a comparison to a predetermined threshold or a greatermeasurement result.

The control unit is also configured to determine channel quality for aplurality of the component carriers.

The control unit is also configured to determine a start of measurementbased on whether the channel quality satisfies a predetermined criteria,and compares a quality level of each resource block with a referencevalue provided by the another information processing apparatus.

The control unit starts measurement when respective quality level ofresource blocks among the component carriers drop below correspondingpredetermined values.

The control unit initiates measurement and sending of measurementinformation according to a procedure that varies depending on a mappingbetween the component carriers and corresponding quality of service foreach data classification.

According to another embodiment, communications between an informationprocessing apparatus and another information processing apparatus isperformed according to a method and includes receiving qualityinformation regarding quality of service for data to be transmitted. Themethod also determines with a processor how to allocate the data oncomponent carriers according to the quality information. The anotherinformation processing apparatus is then notified of allocationinformation that specifies how the data is to be allocated on componentcarriers.

According to another embodiment, communications between an informationprocessing apparatus and another information processing apparatus iscontrolled using step including receiving at the information processingapparatus allocation information that specifies how data to betransmitted is to be allocated among component carriers, and controllingwith a processor a handover procedure according to the allocationinformation.

Advantageous Effects of Invention

As described above, the user equipment, the base station, thecommunication control method, and the radio communication systemaccording to the embodiments of the present invention can efficientlyexecute processing related to a measurement report depending on a QoSrequirement in a radio communication involving the carrier aggregation.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sequence chart to describe a flow of a typical handoverprocedure.

FIG. 2 is an explanatory view to describe an example of a structure of acommunication resource.

FIG. 3 is a schematic view showing an outline of a radio communicationsystem according to an embodiment.

FIG. 4 is an explanatory view to describe an exemplary structure of adata packet.

FIG. 5 is a block diagram showing an example of a configuration of auser equipment according to an embodiment.

FIG. 6 is a block diagram showing an example of a detailed configurationof a radio communication unit according to an embodiment.

FIG. 7A is a block diagram showing an example of a configuration of abase station according to an embodiment.

FIG. 7B is a block diagram showing an example of configurations of abase station and a QoS management node according to an alternativeexample.

FIG. 8 is an explanatory view to describe a first pattern of a mappingbetween a component carrier and a QoS class.

FIG. 9 is an explanatory view to describe a second pattern of a mappingbetween a component carrier and a QoS class.

FIG. 10A is an explanatory view showing a first example in a thirdpattern of a mapping between a component carrier and a QoS class.

FIG. 10B is an explanatory view showing a second example in the thirdpattern of a mapping between a component carrier and a QoS class.

FIG. 10C is an explanatory view showing a third example in the thirdpattern of a mapping between a component carrier and a QoS class.

FIG. 10D is an explanatory view showing a fourth example in the thirdpattern of a mapping between a component carrier and a QoS class.

FIG. 11 is a sequence chart showing an example of a flow of acommunication control process in a radio communication system accordingto an embodiment.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the appended drawings. Note that,in this specification and the appended drawings, structural elementsthat have substantially the same function and structure are denoted withthe same reference numerals, and repeated explanation of thesestructural elements is omitted.

A preferred embodiment of the present invention will be describedhereinafter in the following order.

1. Description of Related Art

1-1. Handover Procedure

1-2. Structure of Communication Resource

2. Outline of Radio Communication System

2-1. Overview of System

2-2. Classification Depending on QoS Requirement

2-3. Channel Quality Report and Measurement Report

3. Exemplary Configurations of Devices According to Embodiment

3-1. Exemplary Configuration of User Equipment

3-2. Exemplary Configuration of Base Station

3-3. Mapping between Component Carrier and Class

4. Flow of Process According to Embodiment

4-1. Exchange of QoS Information

4-2. Determination of Mapping

4-3. Channel Quality Report

4-4. Determination of Start of Measurement

4-5. Measurement Report

5. Summary

<1. Description of Related Art>

(1-1. Handover Procedure)

A technique related to the present invention is described hereinafterwith reference to FIGS. 1 and 2. FIG. 1 shows a flow of a handoverprocedure in conformity with LTE in a radio communication not involvingthe carrier aggregation as an example of a typical handover procedure.In this example, a user equipment (UE), a source base station (sourceeNB), a target base station (target eNB), and a mobility managemententity (MME) are involved in the handover procedure.

As a preliminary step toward a handover, the user equipment firstreports the channel quality of a communication channel between the userequipment and the source base station to the source base station (stepS2). The channel quality may be reported on a regular basis or when thechannel quality falls below a specific reference value. The userequipment can measure the channel quality of the communication channelwith the source base station by receiving a reference signal containedin a downlink channel from the source base station.

Then, the source base station determines the necessity of measurementbased on the quality report received from the user equipment and, ifmeasurement is necessary, allocates measurement gaps to the userequipment (step S4).

Then, the user equipment searches for a downlink channel from aperipheral base station (i.e. performs cell search) during the period ofthe allocated measurement gaps (step S12). Note that the user equipmentcan recognize a peripheral base station to search according to a listthat is provided in advance from the source base station.

When the user equipment acquires synchronization with a downlinkchannel, the user equipment performs measurement by using a referencesignal contained in the downlink channel (step S14). During this period,the source base station restricts an allocation of a data communicationrelated to the user equipment so as to avoid occurrence of datatransmission by the user equipment.

Upon completion of the measurement, the user equipment sends ameasurement report containing a result of the measurement to the sourcebase station (step S22). The result of the measurement contained in themeasurement report may be the average value of measured values over aplurality of times of measurement or the like. Further, the result ofthe measurement may contain data about a plurality of frequency bands.

Receiving the measurement report, the source base station determineswhether a handover should be performed based on the contents of themeasurement report. For example, it can be determined that a handover isnecessary when the channel quality of another base station in theperiphery is higher than the channel quality of the source base stationby a specific threshold or greater. In this case, the source basestation determines to carry out a handover procedure with the relevantanother base station as a target base station, and sends a handoverrequest to the target base station (step S24).

Receiving the handover request, the target base station determineswhether it is possible to accept the user equipment according to theavailability of a communication service offered by itself or the like.When it is possible to accept the user equipment, the target basestation sends a handover request confirm to the source base station(step S26).

Receiving the handover request confirm, the source base station sends ahandover command to the user equipment (step S28). Then, the userequipment acquires synchronization with the downlink channel of thetarget base station (step S32). After that, the user equipment makesrandom access to the target base station by using a random accesschannel in a given time slot (step S34). During this period, the sourcebase station forwards data addressed to the user equipment to the targetbase station (step S36). Then, after succeeded in the random access, theuser equipment sends a handover complete to the target base station(step S42).

Receiving the handover complete, the target base station requests theMME to perform route update for the user equipment (step S44). Uponupdating the route of user data by the MME, the user equipment becomesable to communicate with another device through a new base station (i.e.the target base station). Then, the target base station sendsacknowledgement to the user equipment (step S46). A series of handoverprocedure thereby ends.

(1-2. Structure of Communication Resource)

FIG. 2 shows a structure of a communication resource in LTE as anexample of a structure of a communication resource to which the presentinvention is applicable. Referring to FIG. 2A, the communicationresource in LTE is segmented in the time direction into radio frameseach having a length of 10 msec. One radio frame includes tensub-frames, and one sub-frame is made up of two 0.5 nm slots. In LTE,the sub-frame is one unit of an allocation of a communication resourceto each user equipment in the time direction. Such one unit is called aresource block. One resource block includes twelve sub-carriers in thefrequency direction. Specifically, one resource block has a size of 1msec by 12 sub-carriers in the time-frequency domain. Throughput of datacommunication increases as a larger number of resource blocks isallocated for data communication on condition of the same bandwidth andtime length. Further, in such a structure of a communication resource, apart of radio frame with a given frequency band is reserved as a randomaccess channel. The random access channel can be used for an access to abase station by a user equipment that has changed from an idle mode toan active mode or an initial access to a target base station in ahandover procedure, for example.

<2. Outline of Radio Communication System>

(2-1. Overview of System)

FIG. 3 is a schematic view showing an outline of a radio communicationsystem 1 according to an embodiment of the present invention. Referringto FIG. 3, the radio communication system 1 includes a user equipment100, a base station 200 a and a base station 200 b. It is assumed thatthe base station 200 a is a serving base station for the user equipment100.

The user equipment 100 is located inside a cell 202 a where a radiocommunication service is provided by the base station 200 a. The userequipment 100 can perform a data communication with another userequipment (not shown) via the base station 200 a over a communicationchannel formed by aggregating a plurality of component carriers (i.e. bycarrier aggregation). However, because the distance between the userequipment 100 and the base station 200 a is not short, there is apossibility that a handover is required for the user equipment 100.Further, the user equipment 100 is located inside a cell 202 b where aradio communication service is provided by the base station 200 b.Therefore, the base station 200 b can be a candidate for a target basestation for a handover of the user equipment 100.

The base station 200 a can communicate with the base station 200 bthrough a backhaul link (e.g. X2 interface). Various kinds of messagesin the handover procedure as described with reference to FIG. 1,scheduling information related to the user equipment belonging to eachcell or the like, for example, can be sent and received between the basestation 200 a and the base station 200 b. Further, the base station 200a and the base station 200 b can communicate with an upper node such asa serving gateway (S-GW) or MME through an S1 interface, for example.

It should be noted that, when there is no particular need to distinguishbetween the base station 200 a and the base station 200 b in thefollowing description of the specification, they are collectivelyreferred to as a base station 200 by omitting the alphabetical letter atthe end of the reference symbol. The same applies to the other elements.

(2-2. Classification Depending on QoS Requirement)

In the radio communication system 1, each data signal transmitted overthe above-described communication channel is classified into any of twoor more classes depending on a requirement for the service quality oftraffic (which is referred to hereinafter as a QoS requirement). The twoor more classes depending on the QoS requirement may be four classes(referred to hereinafter as QoS classes) shown in Table 1 below, forexample. In Table 1, a class name, an example of an attribute related toa QoS requirement, and an example of a corresponding service are shownfor each of the four QoS classes.

TABLE 1 Example of Classification Example of Attribute about Class NameQoS Requirement Example of Service Conversational Error Rate VoIPTransfer Delay Video Conference Guaranteed Bit Rate Streaming Error RateReal-Time Video Transfer Delay Distribution Guaranteed Bit RateInteractive Error Rate Web Access Database Retrieval Background ErrorRate E-mail SMS

The first QoS class is a “Conversational” class. For traffic of the“Conversational” class, three attributes of an error rate, a transferdelay and a guaranteed bit rate, for example, can be defined as QoSrequirements to be satisfied.

The error rate can be represented by a service data unit (SDU) errorratio or a residual bit error ratio. The SDU error ratio indicates theratio of the SDU from which an error is detected to the transmittedSDUs. Further, the residual bit error ratio indicates the ratio of thebit not detected at the receiving end to the transmitted data bits. Thetransfer delay indicates the length of delay allowable at the time oftransmission. Further, the guaranteed bit rate indicates a bit rateguaranteed for a user equipment by the radio communication system 1.Note that the maximum bit rate may be used instead of (or in additionto) the guaranteed bit rate.

As is understood from Table 1, for traffic belonging to the“Conversational” class, the radio communication system 1 schedules acommunication resource in such a way that the error rate, the transferdelay and the guaranteed bit rate do not fall below specific referencevalues. An example of a service corresponding to the “Conversational”class is Voice over IP (VoIP), a video conference or the like.

The second QoS class is a “Streaming” class. For traffic of the“Streaming” class also, three attributes of the error rate, the transferdelay and the guaranteed bit rate, for example, can be defined as QoSrequirements to be satisfied. However, reference values of the QoSrequirements for those attributes may be different from those of the“Conversational” class. An example of a service corresponding to the“Streaming” class is real-time video distribution or the like.

The third QoS class is an “Interactive” class. For traffic of the“Interactive” class, only the error rate, for example, can be defined asa QoS requirement to be satisfied. An example of a service correspondingto the “Interactive” class is web access, database retrieval or thelike.

The fourth QoS class is a “Background” class. For traffic of the“Background” class also, only the error rate, for example, can bedefined as a QoS requirement to be satisfied. However, a reference valueof the error rate may be different from that of the “Interactive” class.An example of a service corresponding to the “Background” class isE-mail, short messaging service (SMS) or the like.

It should be noted that the classification of QoS classes shown in Table1 is just an example. For example, another QoS class may be defined forcontrol signaling such as information management signaling (IMS). As forthe QoS class for the control signaling, a stricter (or higher priority)QoS requirement than the above-described QoS class may be imposed. Whichof those QoS classes each data signal should be classified into isdetermined by an individual service application and indicated in aheader of a data packet, for example.

FIG. 4 is an explanatory view to describe an exemplary structure of adata packet that can be transmitted in the radio communication system 1.Referring to FIG. 4, three kinds of data packets 4 a, 4 b and 4 c areshown.

The data packet 4 a is composed of a header section and a data section.The data section of the data packet 4 a contains data bits of a classCi. The class Ci may be any of C1=“Conversational”, C2=“Streaming”,C3=“Interactive” and C4=“Background”. Thus, in this case, the datapacket 4 a is a packet that includes a data signal of a single classonly.

The data section of the data packet 4 b contains data bits of the classCi and a class Cj.

The class Cj may be also any of C1=“Conversational”, C2=“Streaming”,C3=“Interactive” and C4=“Background” (which is, however, different fromthe class Ci). In this manner, data bits of different QoS classes may becontained in combination in one data packet.

The data packet 4 c is a data packet that is distributed to a pluralityof Multiple-Input Multiple-Output (MIMO) streams. A data section of thefirst MIMO stream contains data bits of the class Ci. A data section ofthe second MIMO stream contains data bits of the class Cj. In thismanner, data bits of different QoS classes may be contained in therespective data packets distributed to a plurality of MIMO streams.

In this embodiment, the radio communication system 1 is configured toefficiently execute processing related to a measurement report in aradio communication involving the carrier aggregation in the environmentwhere data signals of a plurality of QoS classes can be mixed.

(2-3. Channel Quality Report and Measurement Report)

The channel quality report is a report that is sent from the userequipment to the serving base station. Based on the channel qualityreport, the serving base station executes link adaptation (includingrate control, power control or the like, for example) of a communicationchannel with the user equipment. As described earlier with reference toFIG. 1, the user equipment measures the channel quality of thecommunication channel by receiving a reference signal contained in adownlink channel from the serving base station and then sends thechannel quality report to the serving base station. The measurement ofthe channel quality for the channel quality report is performed withrespect to each resource block. Further, in this embodiment, the channelquality of each resource block which is measured for the channel qualityreport can be a condition to start measurement for a handover (acondition to trigger measurement).

The measurement report is also a report that is sent from the userequipment to the serving base station. Based on the measurement report,the serving base station determines whether a handover should beperformed or not. As described earlier with reference to FIG. 1, themeasurement of the channel quality for the measurement report isgenerally performed with respect to each communication channel betweenthe serving base station or a peripheral base station and the userequipment. In this embodiment, on the other hand, because eachcommunication channel is composed of a plurality of component carriers,the measurement can be performed with respect to each component carrier.Further, in this embodiment, data signals of a plurality of QoS classescan be mixed in one communication channel. Therefore, by theconfigurations of the user equipment and the base station (and an uppernode) which are described in detail in the following sections,processing from the start of measurement to the sending of a measurementreport is controlled dynamically according to a mapping between acomponent carrier and a QoS class.

<3. Exemplary Configurations of Devices According to Embodiment>

(3-1. Exemplary Configuration of User Equipment)

FIG. 5 is a block diagram showing an example of a configuration of theuser equipment 100 according to the embodiment. Referring to FIG. 5, theuser equipment 100 includes a radio communication unit 110, a signalprocessing unit 150, a controller 160, and a measurement unit 170.

(Radio Communication Unit)

The radio communication unit 110 performs a radio communication with thebase station 200 over a communication channel that is formed byaggregating a plurality of component carriers with use of the carrieraggregation technology.

FIG. 6 is a block diagram showing an example of a more detailedconfiguration of the radio communication unit 110. Referring to FIG. 6,the radio communication unit 110 includes an antenna 112, a switch 114,a low noise amplifier (LNA) 120, a plurality of down-converters 122 a to122 c, a plurality of filters 124 a to 124 c, a plurality ofanalogue-to-digital converters (ADCs) 126 a to 126 c, a demodulationunit 128, a modulation unit 130, a plurality of digital-to-analogueconverters (DACs) 132 a to 132 c, a plurality of filters 134 a to 134 c,a plurality of up-converters 136 a to 136 c, a combiner 138, and a poweramplifier (PA) 140.

The antenna 112 receives a radio signal sent from the base station 200and outputs the received signal to the LNA 120 through the switch 114.The LNA 120 amplifies the received signal. The down-converter 122 a andthe filter 124 a separate a baseband signal of the first componentcarrier (CC1) from the received signal amplified by the LNA 120. Then,the separated baseband signal is converted to a digital signal by theADC 126 a and output to the demodulation unit 128. Likewise, thedown-converter 122 b and the filter 124 b separate a baseband signal ofthe second component carrier (CC2) from the received signal amplified bythe LNA 120. Then, the separated baseband signal is converted to adigital signal by the ADC 126 b and output to the demodulation unit 128.Further, the down-converter 122 c and the filter 124 c separate abaseband signal of the third component carrier (CC3) from the receivedsignal amplified by the LNA 120. Then, the separated baseband signal isconverted to a digital signal by the ADC 126 c and output to thedemodulation unit 128. After that, the demodulation unit 128 generates adata signal by demodulating the baseband signals of the respectivecomponent carriers and outputs the data signal to the signal processingunit 150.

Further, when a data signal is input from the signal processing unit150, the modulation unit 130 modulates the data signal and generatesbaseband signals of the respective component carriers. Among thosebaseband signals, the baseband signal of the first component carrier(CC1) is converted to an analog signal by the DAC 132 a. Then, afrequency component corresponding to the first component carrier in atransmission signal is generated from the analog signal by the filter134 a and the up-converter 136 a. Likewise, the baseband signal of thesecond component carrier (CC2) is converted to an analog signal by theDAC 132 b. Then, a frequency component corresponding to the secondcomponent carrier in the transmission signal is generated from theanalog signal by the filter 134 b and the up-converter 136 b. Further,the baseband signal of the third component carrier (CC3) is converted toan analog signal by the DAC 132 c. Then, a frequency componentcorresponding to the third component carrier in the transmission signalis generated from the analog signal by the filter 134 c and theup-converter 136 c. After that, the generated frequency componentscorresponding to the three component carriers are combined by thecombiner 138, and the transmission signal is formed. The PA 140amplifiers the transmission signal and outputs the transmission signalto the antenna 112 through the switch 114. Then, the antenna 112 sendsthe transmission signal as a radio signal to the base station 200.

Although the case where the radio communication unit 110 handles threecomponent carriers is described in FIG. 6, the number of componentcarriers handled by the radio communication unit 110 may be two, or fouror more.

Further, instead of processing the signals of the respective componentcarriers in the analog region as in the example of FIG. 6, the radiocommunication unit 110 may process the signals of the respectivecomponent carriers in the digital region. In the latter case, at thetime of reception, a digital signal converted by one ADC is separatedinto the signals of the respective component carriers by a digitalfilter. Further, at the time of transmission, after digital signals ofthe respective component carriers are frequency-converted and combined,the signal is converted into an analog signal by one DAC. The load ofthe ADC and the DAC is generally smaller when processing the signals ofthe respective component carriers in the analog region. On the otherhand, when processing the signals of the respective component carriersin the digital region, a sampling frequency for AD/DA conversion ishigher, and the load of the ADC and the DAC can thereby increase.

(Signal Processing Unit)

Referring back to FIG. 5, an example of a configuration of the userequipment 100 is further described below.

The signal processing unit 150 performs signal processing such asdeinterleaving, decoding or error correction on the demodulated datasignal that is input from the radio communication unit 110. Then, thesignal processing unit 150 outputs the processed data signal to an upperlayer. Further, the signal processing unit 150 performs signalprocessing such as encoding or interleaving on the data signal that isinput from the upper layer. Then, the signal processing unit 150 outputsthe processed data signal to the radio communication unit 110.

(Controller)

The controller 160 controls the overall functions of the user equipment100 by using a processing device such as a central processing unit (CPU)or a digital signal processor (DSP). For example, the controller 160controls the timing of data communication by the radio communicationunit 110 according to scheduling information that is received from thebase station 200 by the radio communication unit 110. Further, thecontroller 160 controls the measurement unit 170 to measure the channelquality of each resource block by using a reference signal from the basestation 200, which is a serving base station, and sends a channelquality report to the base station 200 through the radio communicationunit 110. Further, the controller 160 receives control informationrelated to a mapping between each of component carriers and the QoSclass of each data signal from the base station 200 through the radiocommunication unit 110. The control information may be the sameinformation as or different information from the above-describedscheduling information. Then, the controller 160 controls at least oneof the measurement of a channel quality by the measurement unit 170 andthe sending of a measurement report according to a procedure whichvaries depending on the control information. The processing related tothe measurement report is described in further detail later.

(Measurement Unit)

The measurement unit 170 measures the channel quality of each resourceblock in a component carrier by using a reference signal from the basestation 200 according to control from the controller 160, for example.Further, the measurement unit 170 executes measurement for a handoverwith respect to each component carrier according to control from thecontroller 160. A result of the measurement executed by the measurementunit 170 is converted to a specific format for a measurement report bythe controller 160 and sent to the base station 200 through the radiocommunication unit 110. After that, based on the measurement report, thebase station 200 determines whether a handover should be performed ornot for the user equipment 100.

Note that the controller 160 may make the measurement unit 170 startmeasurement at regular intervals. Alternatively, in this embodiment, thecontroller 160 may make the measurement unit 170 start measurement whenthe channel quality of each resource block that is measured for achannel quality report by the measurement unit 170 does not satisfy aspecific reference. In any case, the controller 160 may create ameasurement report and send it to the base station 200 when the channelquality of another base station in the periphery is higher than thechannel quality of the serving base station by a specific threshold orgreater as a result of the measurement, for example. Herein, thresholdvalues (or reference values) varying for each component carrier may beused, for example. Note that, as described later, by which condition themeasurement should be started (i.e. on a regular basis, according to aspecific criterion or the like), a reference value to be used and so oncan be specified by the base station 200.

(3-2. Exemplary Configuration of Base Station)

FIG. 7A is a block diagram showing an example of a configuration of thebase station 200 according to the embodiment. Referring to FIG. 7A, thebase station 200 includes a radio communication unit 210, an interfaceunit 250, a storage unit 260, a controller 270 and a QoS manager 280.

(Radio Communication Unit)

A specific configuration of the radio communication unit 210 may besimilar to the configuration of the radio communication unit 110 of theuser equipment 100 which is described earlier with reference to FIG. 6,although the number of component carriers to be supported, a requirementof processing performance or the like is different. The radiocommunication unit 210 performs a radio communication with the userequipment over a communication channel that is formed by aggregating aplurality of component carriers with use of the carrier aggregationtechnology.

(Interface Unit)

The interface unit 250 mediates a communication between the radiocommunication unit 210, the controller 270 or the QoS manager 280 and anupper node through the S1 interface illustrated in FIG. 3, for example.Further, the interface unit 250 mediates a communication between theradio communication unit 210, the controller 270 or the QoS manager 280and another base station through the X2 interface illustrated in FIG. 3,for example.

(Storage Unit)

The storage unit 260 holds CC management data that indicates whichcomponent carrier each user equipment is using for communication withrespect to each of the user equipments belonging to the cell of the basestation 200 by using a storage medium such as a hard disk, semiconductormemory or the like. Such CC management data can be updated by thecontroller 270 when an additional user equipment joins the cell of thebase station 200 or when the existing user equipment changes a componentcarrier. Thus, the controller 270 can recognize which component carrierthe user equipment 100 is using by referring to the CC management data.

Further, the storage unit 260 stores link characteristics data thatindicates the characteristics of each link which is generated by thecontroller 270 based on the channel quality report sent from the userequipment 100. Further, the storage unit 260 stores QoS data indicatingthe attribute value, such as an error rate, a transfer delay or aguaranteed bit rate, of each QoS class which should be satisfied in eachtraffic. The link characteristics data and the QoS data are used at thetime of scheduling of a communication resource in order to determine amapping between each of component carriers and the QoS class of eachdata signal.

(Controller)

The controller 270 controls the overall functions of the base station200 by using a processing device such as a CPU or a DSP. For example,the controller 270 schedules a communication resource for datatransmission by the user equipment 100 based on the attribute value ofeach QoS class which should be satisfied in each traffic and which isnotified from the QoS manager 280. For example, for traffic on which astrict requirement for transfer delay is imposed, it is preferred thatthe controller 270 allocates communication resources in parallel alongthe frequency direction as much as possible. By the scheduling of acommunication resource by the controller 270, a mapping between each ofcomponent carriers and the QoS class of each data signal is defined.Three typical patterns (six variations) of such a mapping are furtherdescribed later with examples.

Further, the controller 270 determines whether a handover to anotherbase station by the user equipment 100 should be performed or not byusing the above-described measurement report that is sent from the userequipment 100. Specifically, the controller 270 sends controlinformation related to a mapping between each of component carriers andthe QoS class of each data signal which is specified by the schedulingto the user equipment 100 through the radio communication unit 210.Furthermore, the controller 270 receives the measurement report that iscreated and sent by the user equipment 100 according to a procedurewhich varies depending on the control information through the radiocommunication unit 210. Then, the controller 270 determines whether ahandover to another base station by the user equipment 100 should beperformed or not by using the received measurement report.

(QoS Manager)

The QoS manager 280 commonly manages a QoS requirement to be satisfiedin each traffic by using QoS data stored in the storage unit 260, forexample. Further, prior to scheduling of a communication resource, theQoS manager 280 notifies the controller 270 of a QoS requirement for adata signal as a target of the scheduling. At this time, when there is apossibility that the QoS requirement is not satisfied, the QoS manager280 negotiates with another base station or an upper node so as tosatisfy the QoS requirement by a change in a path of a radio accessnetwork (RAN), utilization of a wired link or the like.

Note that the QoS manager 280 may be placed in an upper node of the basestation 200, rather than placed in the base station 200. The upper nodeof the base station 200 is a node corresponding to a serving gateway,MME or the like, for example. FIG. 7B is a block diagram showing suchanother example of a configuration. In FIG. 7B, the QoS manager 280,among the components of the base station 200 shown in FIG. 7A, is placedin an upper node 300 of the base station 200. Referring to FIG. 7B, thebase station 200 includes the radio communication unit 210, theinterface unit 250, the storage unit 260 and the controller 270.Further, the upper node 300 includes the QoS manager 280 and a storageunit 360. The storage unit 360 stores at least QoS data among the datastored in the storage unit 260 described above, for example.

(3-3. Mapping Between Component Carrier and Class)

Typical patterns of a mapping between each of component carriers and theQoS class of each data signal are described hereinafter with referenceto FIGS. 8 to 10D.

(First Pattern)

FIG. 8 is an explanatory view to describe a first pattern (pattern P1)of a mapping between each of component carriers and the QoS class ofeach data signal. The first pattern is a pattern that can be employedwhen a data signal to be transmitted contains data bits of a single QoSclass only.

Referring to FIG. 8, a data signal contains data bits that belong to theclass C1 only. The controller 270 of the base station 200 evenly orunevenly distributes those data bits to the respective componentcarriers depending on a QoS requirement notified from the QoS manager280. In the example of FIG. 8, resource blocks in the component carriersCC1, CC2 and CC2 are scheduled unevenly with a ratio of 3:2:1,respectively. The ratio can be determined depending on the channelquality of each of the component carriers or the availability ofresources, for example.

(Second Pattern)

FIG. 9 is an explanatory view to describe a second pattern (pattern P2)of a mapping between each of component carriers and the QoS class ofeach data signal. The second pattern is a pattern that can be employedin the case where a data signal to be transmitted contains data bits ofa plurality of QoS classes.

Referring to FIG. 9, a data signal contains data bits that belong to theclasses C1, C2 and C3. The controller 270 of the base station 200distributes those data bits to the respective component carriers in sucha way that data bits classified into different classes are transmittedon different component carriers. For example, when the QoS requirementof the class C1 is the strictest (has the highest priority), thecontroller 270 allocates the data bit belonging to the class C1 to thecomponent carrier CC1 with the highest channel quality. Further, thecontroller 270 allocates the data bit belonging to the class C2 whoseQoS requirement is the second strictest (has the second highestpriority) to the component carrier CC2 with the second highest channelquality. Furthermore, the controller 270 allocates the data bitbelonging to the class C3 whose QoS requirement is the least strict tothe remaining component carrier CC3. In the second pattern, because adata signal that belongs to one kind of QoS class only is transmitted inone component carrier, a cost for QoS management is reduced.

(Third Pattern)

FIGS. 10A to 10D are explanatory views to describe a third pattern of amapping between each of component carriers and the QoS class of eachdata signal. The third pattern, like the second pattern, is a patternthat can be employed in the case where a data signal to be transmittedcontains data bits of a plurality of QoS classes. However, in the thirdpattern, data bits classified into different classes from one anothercan be distributed to a single component carrier. That is, according tothis pattern, a single component carrier can be shared by data bits ofdifferent classes. Hereinafter, four variations of the third pattern,i.e. patterns P3 a to P3 d, are described sequentially.

Referring to FIG. 10A (pattern P3 a), a data signal contains data bitsthat belong to the classes C1, C2 and C3. The controller 270 of the basestation 200 distributes those data bits to the respective componentcarriers with the same ratio. Specifically, the ratio of the data bitsrespectively belonging to the classes C1, C2 and C3 which aredistributed to the component carrier CC1 is the same as thecorresponding ratio in the component carriers CC2 and CC3. In thepattern P3 a, because distribution of data bits can be determined by thecommon ratio, mapping is simplified and a processing cost for schedulingcan be reduced. Further, by the effect of interleaving, it is expectedto obtain better link characteristics than when simply distributing databits belonging to the same class to the same component carrier.

Referring to FIG. 10B (pattern P3 b), a data signal contains data bitsthat belong to the classes C1, C2 and C3. The controller 270 of the basestation 200 distributes those data bits to the respective componentcarriers with a different ratio. In the example of FIG. 10B, the databits respectively belonging to the classes C1, C2 and C3 are distributedto the component carrier CC1. On the other hand, the data bit belongingto the class C1 only is distributed to the component carrier CC2.Further, the data bits respectively belonging to the classes C2 and C3only are distributed to the component carrier CC3. In the pattern P3 b,because the amount of the communication resource that is allocated toeach component carrier can be increased or decreased depending on thestrictness (priority) of a QoS requirement, more flexible scheduling canbe performed to satisfy the QoS requirement.

Referring to FIG. 10C (pattern P3 c), a data signal contains data bitsthat belong to the classes C1, C2 and C3. The controller 270 of the basestation 200 distributes those data bits to one component carrier. Thepattern P3 c can be employed when the channel quality of one componentcarrier is significantly higher than the channel quality of the othercomponent carriers and there are sufficient available resources.

Referring to FIG. 10D (pattern P3 d), a data signal contains data bitsthat belong to the classes C1, C2 and C3. The controller 270 of the basestation 200 distributes those data bits to the respective componentcarriers with a different ratio. Further, in the pattern P3 d, unlikethe pattern P3 b shown in FIG. 10B, the controller 270 distributes databits that belong to different classes to one resource block. In theexample of FIG. 10D, the data bits respectively belonging to the classesC1, C2 and C3 are distributed to the component carrier CC2. Then, thedata bits respectively belonging to the classes C1 and C2 aredistributed to a resource block RB1 of the component carrier CC2.Further, the data bits respectively belonging to the classes C1 and C3are distributed to a resource block RB2 of the component carrier CC2. Inthe pattern P3 d, still more flexible scheduling in units of resourceblocks can be performed.

(Selection of Mapping Pattern)

At the time of scheduling of a communication resource, the controller270 can select which of the above-described patterns should be employeddepending on variation of the channel quality among the componentcarriers or the availability of resources of the respective componentcarriers. Table 2 below shows an example of a selection criterion of themapping pattern. Note that the case where a data signal to betransmitted contains data bits of a plurality of QoS classes is mainlydescribed hereinbelow.

TABLE 2 Example of Selection Criterion of Mapping Pattern Variation ofQuality All CCs satisfy specific Some CCs do not satisfy ResourceAvailability criterion specific criterion All CCs satisfy specific Case1-1 Case 1-2 criterion (Single class→P1) Pattern P3d Multiple classes→Pattern P2 or P3a Some CCs do not Case 2-1 Case 2-2 satisfy specificcriterion Pattern P3b Pattern P3c

In Table 2, the availability of resources can be evaluated based on aresource usage rate of each of the component carriers, for example.Further, the variation of quality can be evaluated based on the channelquality of each of the component carriers that is obtained through thechannel quality report, for example.

For example, it is assumed as the availability of resources that theusage rate is lower than a specific reference (i.e. there are sufficientavailable resources) for all component carriers. Further, when thechannel quality is higher than a specific reference for all componentcarriers, the controller 270 can select the pattern P2 or the pattern P3a (case 1-1). In the case where it is desirable to reduce a costnecessary for QoS management, the pattern P2 may be selected. On theother hand, in the case where it is desirable to improve the linkcharacteristics, the pattern P3 may be selected.

Further, when the availability of resources is the same as that of thecase 1-1 and there is a component carrier whose channel quality does notsatisfy a specific reference, the controller 270 can select the patternP3 d (case 1-2).

Furthermore, when, as the availability of resources, there is acomponent carrier whose usage rate is higher than a specific reference(i.e. there is no sufficient available resource) and the channel qualityis higher than a specific reference for all component carriers, thecontroller 270 can select the pattern P3 b (case 2-1). Further, when theavailability of resources is the same as that of the case 2-1 and thereis a component carrier whose channel quality does not satisfy a specificreference, the controller 270 can select the pattern P3 c (case 2-2).

The controller 270 of the base station 200 determines a mapping betweeneach of the component carriers and the QoS class of each data signal byusing such a selection criterion as an example. Then, the controller 270sends control information related to the mapping to the user equipment100 through the radio communication unit 210. The control informationrelated to the mapping may be scheduling information that is deliveredthrough a control channel or a broadcast channel of a downlink, forexample. Preferably, the control information related to the mappingindicates a mapping between a resource block that is contained in eachcomponent carrier and the QoS class of each data signal that istransmitted in the resource block. Further, the control informationrelated to the mapping may contain an identification code foridentifying the employed mapping pattern. After that, as describedabove, the controller 160 of the user equipment 100 executes measurementaccording to a procedure which varies depending on the controlinformation sent from the base station 200 and sends a measurementreport to the base station 200. In the following section, a flow of aprocess according to such patterns of mapping is described in detail.

<4. Flow of Process According to Embodiment>

FIG. 11 is a sequence chart showing an example of a flow of acommunication control process in the radio communication system 1according to the embodiment. Referring to FIG. 11, a communicationcontrol process as an example is shown along three lanes respectivelycorresponding to the user equipment (UE) 100 and the controller 270 andthe QoS manager 280 of the base station (eNB) 200.

(4-1. Exchange of QoS Information)

First, prior to scheduling of a communication resource by the controller270, information related to a QoS requirement is exchanged between thecontroller 270 and the QoS manager 280 (step S102). For example, whentraffic of the “Conversational” class or the “Streaming” class exists,the QoS manager 280 notifies the value of (allowable) transfer delay foreach class to the controller 270. Further, the QoS manager 280 notifiesan index value of an error rate such as an SDU error ratio or a biterror ratio to the controller 270. Alternatively, the QoS manager 280may notify a guaranteed bit rate to the controller 270, and thecontroller 270 may calculate an index value of an error rate to besatisfied based on the guaranteed bit rate. In response to such anotification, the controller 270 reply to the QoS manager 280 as towhether it is possible to schedule a communication resource so as tosatisfy the QoS requirement. When it is difficult to make scheduling tosatisfy the QoS requirement, the QoS manager 280 may negotiate withanother base station or an upper node about a change in a path of RAN,utilization of a wired link or the like. Alternatively, the QoS manager280 may determine to leave transmission of traffic of a class with arelatively low priority, such as the “Interactive” class or the“Background” class, until later.

(4-2. Determination of Mapping)

Then, the controller 270 determines a mapping between each of componentcarriers and the QoS class of each data signal for the user equipment100 based on the QoS requirement notified from the QoS manager 280, andschedules a communication resource (step S104). The determination of themapping is made depending on variation of the channel quality among thecomponent carriers and the availability of resources of the respectivecomponent carriers as described above. Typically, variation of thechannel quality among the component carriers may be figured out througha preceding channel quality report (step S114 described later) in therepetitive communication control process of FIG. 11. Alternatively, thecontroller 270 of the base station 200 may request, to the userequipment 100, an auxiliary channel quality report used for determininga mapping at step S104, separately from the step S114. After that, thecontroller 270 delivers scheduling information indicating a result ofthe mapping to the user equipment 100 through a control channel or abroadcast channel of a downlink (step S106). In this step, thecontroller 270 may explicitly notify an identification code foridentifying a pattern of mapping to the user equipment 100. Further,when data signals of a plurality of QoS classes are mixed, thecontroller 270 may additionally notify an index value such as theminimum necessary signal to interference and noise ratio (SINR) or theminimum reception power for each of the QoS classes to the userequipment 100.

(4-3. Channel Quality Report)

Meanwhile, the user equipment 100 measures the channel quality of eachresource bock by receiving a reference signal contained in each resourceblock of each component carrier of a downlink channel from the basestation 200 (step S112). Then, the user equipment 100 transmits achannel quality report that is created by using the measured qualitylevel to the base station 200 (step S114). The contents of the channelquality report can vary depending on the pattern of mapping which isknown from the control information that has been acquired from the basestation 200 by the user equipment 100 in the step S106. The contents ofthe channel quality report that correspond to each pattern of mappingare described hereinbelow.

(In First Pattern)

In the first pattern illustrated in FIG. 8, a data signal of one kind ofQoS class only is mapped to all of the component carriers constituting acommunication channel. In this case, the user equipment 100 may includeonly the representative value (e.g. the average value, the minimum valueor the like) of the quality levels of all resource blocks of all thecomponent carriers, for example, into the channel quality report.

(In Second Pattern)

In the second pattern illustrated in FIG. 9, a data signal of one kindof QoS class is mapped to each single component carrier constituting acommunication channel. In this case, the user equipment 100 maydetermine the representative value of the quality levels of all resourceblocks in each component carrier for each of the component carriers andinclude those representative values into the channel quality report, forexample. Alternatively, the user equipment 100 may include only therepresentative value with the lowest quality level among therepresentative values of the quality levels of the respective componentcarriers into the channel quality report, for example. Further, the userequipment 100 may include the representative value of the quality levelsfor the component carrier corresponding to a QoS class with a highpriority (e.g. the “Conversational” class, the “Streaming” class or thelike), for example, into the channel quality report.

Further, the user equipment 100 may calculate one representative valuein the whole communication channel by weighted summing of therepresentative values of the quality levels of the respective componentcarriers according to the following expression (1) by using a weightdepending on a QoS requirement of each QoS class, for example. Theweight depending on a QoS requirement of each QoS class may be a valuedepending on an index value such as the minimum necessary SINR or theminimum reception power that is notified from the base station 200, forexample.

$\begin{matrix}{{{Expression}\mspace{14mu} 1}\mspace{616mu}} & \; \\{Q_{all} = {\sum\limits_{i = 1}^{n}{w_{cci}Q_{cci}}}} & (1)\end{matrix}$

In the expression (1), Q_(a11) is the representative value of thequality levels which is a single value calculated in the wholecommunication channel. Further, i is a component carrier number, n isthe number of component carriers, w_(cci) is a weight of each QoS classcorresponding to each component carrier, and Q_(cci) is therepresentative value of the quality levels of each component carrier.The single representative value of the quality levels in the wholecommunication channel which is calculated in this manner may be alsoincluded into the channel quality report.

(In Third Pattern)

In the third pattern illustrated in FIGS. 10A to 10D, there is apossibility that data signals of a plurality of kinds of QoS classes ismapped to a single component carrier. In this case, the user equipment100 may determine the representative value of the quality levels ofresource blocks corresponding to a QoS class with a high priority ineach component carrier for each of the component carriers and includethose representative values into the channel quality report, forexample. Alternatively, the user equipment 100 may determine therepresentative value of the quality levels of the respective QoS classesin a plurality of component carriers, for example, and include therepresentative values of the respective QoS classes into the channelquality report.

Further, the user equipment 100 may calculate a single representativevalue in the whole communication channel by weighted summing of therepresentative values of the quality levels of the respective QoSclasses according to the following expression (2) by using a weightdepending on a QoS requirement of each QoS class, for example. Theweight depending on a QoS requirement of each QoS class may be a valuedepending on an index value such as the minimum necessary SINR or theminimum reception power that is notified from the base station 200, forexample, as described above.

$\begin{matrix}{{{Expression}\mspace{14mu} 2}\mspace{616mu}} & \; \\{Q_{all} = {\sum\limits_{j = 1}^{m}{v_{c\_ j}Q_{c\_ j}}}} & (2)\end{matrix}$

In the expression (2), Q_(a11) is the representative value of thequality levels which is a single value calculated in the wholecommunication channel. Further, j is a class number, n is the number ofclasses, v_(c) _(—) _(j) is a weight of each QoS class, and Q_(c) _(—)_(j) is the representative value of the quality levels of each QoSclass. The single representative value of the quality levels in thewhole communication channel which is calculated in this manner may bealso included into the channel quality report.

As described above, by dynamically calculating the representative valueof the quality levels to be included into the channel quality reportaccording to a mapping between each of the component carriers and theQoS class of each data signal, it is possible to reduce the amount ofthe communication resource necessary for the channel quality report.Further, in a radio communication involving the carrier aggregationalso, it is possible to efficiently create the effective channel qualityreport.

(4-4. Determination of Start of Measurement)

Then, measurement gaps are allocated to the user equipment 100 by thecontroller 270 of the base station 200 (step S116). Further, thecontroller 270 notifies the user equipment 100 of information to be usedfor execution of measurement by the user equipment 100, such asinformation indicating by which condition measurement should be startedand a reference value to be used, for example.

After that, the user equipment 100 makes a determination about the startof measurement (step S122). For example, when it is notified from thebase station 200 that measurement should be executed on a regular basis,the user equipment 100 starts measurement at regular intervals countedby a timer. On the other hand, when the start of measurement isdetermined based on whether the channel quality satisfies a specificreference or not, the user equipment 100 compares the quality level ofeach resource block measured for the channel quality report with areference value notified from the base station 200. The specificreference in the latter case may be a reference which varies dependingon the pattern of mapping. The details of the determination about thestart of measurement which correspond to each pattern of mapping aredescribed hereinbelow.

(In First Pattern)

In the first pattern illustrated in FIG. 8, a data signal of one kind ofQoS class only is mapped to all of the component carriers constituting acommunication channel as described above. In this case, the userequipment 100 may determine to start measurement when the quality levelof any one resource block among all the component carriers becomes lowerthan a reference value.

Herein, reference values varying from one component carrier to anothermay be used, for example. The reference values used herein may varydepending on the number of resource blocks allocated to each componentcarrier. Alternatively, the user equipment 100 may determine to startmeasurement when the representative value of the quality levels in anyone component carrier (the minimum value, the average value or the likeof the quality level of each resource block) becomes lower than areference value, for example. Further, the user equipment 100 maydetermine to start measurement when the representative value of thequality levels of a component carrier to which the most communicationresources are allocated becomes lower than a reference value.

(In Second Pattern)

In the second pattern illustrated in FIG. 9, a data signal of one kindof QoS class is mapped to each of the component carriers constituting acommunication channel as described above. In this case, the userequipment 100 may use, for example, reference values varying from onecomponent carrier to another depending on the priority of correspondingQoS class as reference values for comparison to the quality levels. Theuser equipment 100 may determine to start measurement when therepresentative value of the quality levels in a component carriercorresponding to a QoS class with a high priority becomes lower than areference value, for example, other than the criterion of the firstpattern.

(In Third Pattern)

In the third pattern illustrated in FIGS. 10A to 10D, there is apossibility that a data signal of a plurality of kinds of QoS classes ismapped to one component carrier as described above. In this case, theuser equipment 100 may use, for example, reference values varyingdepending on whether the component carrier has a resource blockcorresponding to a QoS class with high priority or not as referencevalues for comparison to the quality levels. The user equipment 100 maydetermine to start measurement when the quality level of any oneresource block corresponding to a QoS class with a high priority becomeslower than a reference value, for example, other than the criterion ofthe first pattern. Alternatively, the user equipment 100 may determineto start measurement when the representative value of the quality levelsin a plurality of component carriers for a QoS class with a highpriority (the minimum value, the average value or the like of thequality level of each resource block) becomes lower than a referencevalue, for example.

As described above, by determining the necessity of measurement by usinga criterion which varies depending on the pattern of mapping, it ispossible to reduce a cost necessary for measurement as well asmaintaining the appropriate service quality in a radio communicationinvolving the carrier aggregation. A flexible control of the procedureaccording to QoS requirements is also enabled by using a criterion whichvaries from one component carrier to another.

(4-5. Measurement Report)

Then, after acquiring synchronization with a downlink channel of aperipherally base station by cell search, the user equipment 100performs measurement by using a reference signal contained in thedownlink channel (step S124). The user equipment 100 then sends ameasurement report to the base station 200 according to a result of themeasurement (step S126). After that, the base station 200 determineswhether a handover should be performed or not based on the contents ofthe measurement report. Further, the user equipment 100 may determinewhether a measurement report should be sent to the base station 200 ornot according to a result of the measurement. The determination as towhether a measurement report should be sent or not can be made accordingto a criterion which varies depending on a mapping between each of thecomponent carriers and the QoS class of each data signal. The details ofthe determination about the sending of a measurement report whichcorrespond to each pattern of mapping are described hereinbelow.

(In First Pattern)

In the first pattern illustrated in FIG. 8, a data signal of one kind ofQoS class only is mapped to all of the component carriers constituting acommunication channel as described above. In this case, the userequipment 100 may determine to send a measurement report when thechannel quality of another base station in the periphery is higher thanthe channel quality of the base station 200 by a specific threshold orgreater for any one component carrier, for example. Any one componentcarrier may be a component carrier whose channel quality with the basestation 200 a (i.e. the serving base station) is the highest, forexample. Alternatively, any one component carrier may be a componentcarrier to which the most resource blocks are allocated. Furthermore,threshold values varying from one component carrier to another may beset. In this case, measurement report may be sent when the difference inchannel quality exceeds respective corresponding threshold value for anyone or all of the component carriers. For example, threshold valuesvarying depending on the number of resource blocks allocated to eachcomponent carrier may be set.

(In Second Pattern)

In the second pattern illustrated in FIG. 9, a data signal of one kindof QoS class is mapped to each of the component carriers constituting acommunication channel as described above. In this case, the userequipment 100 may determine to send a measurement report when thechannel quality of another base station in the periphery is higher thanthe channel quality of the base station 200 by a specific threshold orgreater for a component carrier corresponding to a QoS class with a highpriority, for example, other than the criterion of the first pattern.Furthermore, threshold values varying from one component carrier toanother may be set. In this case, measurement report may be sent whenthe difference in channel quality exceeds respective correspondingthreshold value for any one or all of the component carriers. Forexample, threshold values varying depending on the priority ofcorresponding QoS class may be set.

(In Third Pattern)

In the third pattern illustrated in FIGS. 10A to 10D, there is apossibility that a data signal of a plurality of kinds of QoS classes ismapped to one component carrier as described above. In this case, theuser equipment 100 may determine to send a measurement report when thechannel quality of another base station in the periphery is higher thanthe channel quality of the base station 200 by a specific threshold orgreater for any one component carrier having a resource blockcorresponding to a QoS class with a high priority, for example, otherthan the criterion of the first pattern. Furthermore, threshold valuesvarying from one component carrier to another may be set. In this case,measurement report may be sent when the difference in channel qualityexceeds respective corresponding threshold value for any one or all ofthe component carriers. For example, a lower threshold value may be setfor a component carrier having a resource block corresponding to a QoSclass with high priority, and a higher threshold value may be set forthe other component carriers.

As described above, by determining whether a measurement report shouldbe sent or not by using a criterion which varies depending on thepattern of mapping, it is possible to suppress consumption of thecommunication resource by the sending of a measurement report as well asmaintaining the appropriate service quality in a radio communicationinvolving the carrier aggregation. Further, in the case of not sending ameasurement report, it is possible to omit the measurement reportcreation process. A flexible control of the procedure according to QoSrequirements is also enabled by using a criterion which varies from onecomponent carrier to another.

(5. Summary)

The radio communication system 1 according to one embodiment of thepresent invention is described above with reference to FIGS. 3 to 11.According to the embodiment, each data signal transmitted on a pluralityof component carriers that constitute one communication channel by thecarrier aggregation technology is classified into any QoS classdepending on a QoS requirement. Then, the execution of measurement andthe sending of a measurement report are controlled in the user equipment100 according to a procedure which varies depending on a mapping betweeneach of the component carriers and the QoS class of each data signal. Itis thereby possible to efficiently execute processing from the start ofmeasurement to the sending of a measurement report without degrading theservice quality as much as possible in a radio communication involvingthe carrier aggregation.

For example, as described above, by controlling determination as towhether a measurement report should be sent or not according to aprocedure which varies depending on mapping described above, consumptionof the communication resource for the sending of the measurement reportis suppressed. Further, a cost necessary for creation of the measurementreport can be reduced. Furthermore, by determining the necessity ofmeasurement according to a criterion which varies depending on mappingdescribed above, it is possible to reduce a cost necessary formeasurement as well as maintaining the appropriate service quality. Inaddition, by dynamically calculating the value of the quality level tobe included into a channel quality report according to mapping describedabove, it is possible to reduce the amount of the communication resourcenecessary for the channel quality report as well as maintaining theeffectiveness of the channel quality report.

It should be noted that a series of processing according to theembodiment described in this specification may be implemented on eitherhardware or software. In the case of executing a series or part ofprocessing on software, a program constituting the software is stored ina storage medium such as a hard disk or semiconductor memory, read intorandom access memory (RAM) at the time of execution and then executed bya processing device such as a CPU or a DSP.

Although preferred embodiments of the present invention are described indetail above with reference to the appended drawings, the presentinvention is not limited thereto. It should be understood by thoseskilled in the art that various modifications, combinations,sub-combinations and alterations may occur depending on designrequirements and other factors insofar as they are within the scope ofthe appended claims or the equivalents thereof.

The present application contains subject matters related to thatdisclosed in Japanese Priority Patent Application JP 2009-263004 filedin the Japan Patent Office on Nov. 18, 2009, and Japanese PriorityPatent Application JP 2010-219635, the entire content of both of whichare hereby incorporated by reference.

REFERENCE SIGNS LIST

-   -   1 RADIO COMMUNICATION SYSTEM    -   100 USER EQUIPMENT    -   110 RADIO COMMUNICATION UNIT    -   160 CONTROLLER    -   170 MEASUREMENT UNIT    -   200 BASE STATION    -   210 RADIO COMMUNICATION UNIT    -   260 STORAGE UNIT    -   270 CONTROLLER    -   280 QoS MANAGER

1. An information processing apparatus for communicating with anotherinformation processing apparatus, comprising: a receiver configured toreceive quality information regarding quality of service for data to betransmitted; an allocating unit configured to determine how to allocatethe data on component carriers according to the quality information; anda notification unit configured to notify said another informationprocessing apparatus of allocation information that specifies how thedata is to be allocated on the component carriers.
 2. The apparatus ofclaim 1, wherein said allocating unit allocates said data differentlyaccording to a quality information associated with a data classificationfor said data.
 3. The apparatus of claim 1, wherein the allocating unitis configured to mix data with different quality of service criteria ona common communication channel using carrier aggregation of saidcomponent carriers.
 4. The apparatus of claim 1, wherein a mapping ofcomponent carriers to quality of services classifications for data setby said allocating unit enables dynamic control at said anotherinformation processing unit from a time of starting channel qualitymeasurement to providing a measurement report to said informationprocessing apparatus.
 5. The apparatus of claim 4, further comprising: aprocessor configured to determine whether to perform a handover for saidanother information processing apparatus based on whether themeasurement report indicates that a better channel quality is availableto said another information processing apparatus from a peripheralinformation processing apparatus, said better channel quality beingbetter with respect to a predetermined threshold.
 6. The apparatus ofclaim 5, wherein the predetermined threshold being varied for respectiveof the component carriers.
 7. The apparatus of claim 1, wherein: saidallocating unit is configured to select a mapping pattern for allocatingdata on the component carriers depending on one of variation of channelquality among the component carriers and resource availability of therespective component carriers.
 8. The apparatus of claim 7, wherein:said allocating unit determines the variation of channel quality amongcomponent carriers via a preceding channel quality report provided bysaid another information processing apparatus.
 9. The apparatus of claim7, wherein: said allocating unit determines the variation of channelquality among component carriers by requesting an auxiliary channelquality report from the another information processing apparatus.
 10. Aninformation processing apparatus for communicating with anotherinformation processing apparatus using a plurality of componentcarriers, comprising: a receiver configured to receive allocationinformation that specifies how data to be transmitted is to be allocatedamong component carriers; and a processing unit configured to execute aprocess in order to conduct a handover procedure according to theallocation information.
 11. The apparatus of claim 10, wherein saidprocess includes at least one of: transmitting a channel quality reportor measurement report, and determining timing when a measurement starts.12. The apparatus of claim 10, wherein said allocation informationincludes information about how data is allocated on component carriersbased on quality of service criteria.
 13. The apparatus of claim 12,wherein said data is categorized into one of a plurality of quality ofservice classifications.
 14. The apparatus of claim 10, wherein saidcontrol unit sends measurement data to said another informationprocessing apparatus when said control unit determines that a channelquality available from a peripheral information processing apparatus ishigher than a channel quality from the another information processingapparatus.
 15. The apparatus of claim 14, wherein said control unitdetermines the channel quality being higher based on a comparison to apredetermined threshold or a greater measurement result.
 16. Theapparatus of claim 14, wherein the control unit determines channelquality for a plurality of the component carriers.
 17. The apparatus ofclaim 14, wherein the control unit determines a start of measurementbased on whether the channel quality satisfies a predetermined criteria,and compares a quality level of each resource block with a referencevalue provided by the another information processing apparatus.
 18. Theapparatus of claim 17, wherein the control unit starts measurement whenrespective quality level of resource blocks among the component carriersdrop below corresponding predetermined values.
 19. The apparatus ofclaim 10, wherein said control unit initiates measurement and sending ofmeasurement information according to a procedure that varies dependingon a mapping between the component carriers and corresponding quality ofservice for each data classification.
 20. A method for controllingcommunications between an information processing apparatus and anotherinformation processing apparatus, comprising: receiving qualityinformation regarding quality of service for data to be transmitted;determining with a processor how to allocate the data on componentcarriers according to the quality information; and notifying saidanother information processing apparatus of allocation information thatspecifies how the data is to be allocated on component carriers.
 21. Amethod for controlling communications between an information processingapparatus and another information processing apparatus, comprising:receiving at the information processing apparatus allocation informationthat specifies how data to be transmitted is to be allocated amongcomponent carriers; and executing with a processor a process in order toconduct a handover procedure according to the allocation information.22. The method of claim 21, wherein said process includes at least oneof: transmitting a channel quality report or measurement report, anddetermining timing when a measurement starts.